The digital trunk communication system primarily comprises a Terrestrial Trunked Radio (TETRA) system, an Integrated Digital Enhanced Networks (iDEN) system, a Global Open Trunking Architecture (GoTa) system, and a GT800 system, etc. Group call services are most basic services provided by the digital trunk communication system. The group call services allow a trunk user terminal to set up a group call to a certain group of trunk user terminals which belong to a given area. During a call setup using a half duplex mode, the system allocates a group call channel to each cell in the group call area respectively, wherein the uplink is only used by a calling trunk user terminal, and all called trunk user terminals monitor the downlink.
However, in the LTE network, there is currently also a lack of networking policy which can support the requirements of trunk communication, and therefore, a point-to-multipoint half duplex real-time communication operation mode cannot be supported, and the objective use requirements of the existing trunk functions cannot be met. In the exiting LTE system, an Access Stratum (AS) between a User Equipment (UE) and an evolved Node B (eNB) can only implement a point-to-point service. Even for a telephone conference, it also needs to set up dedicated bearer resources for each user, thereby resulting in a waste of resources.